The present invention relates to a moving image data compression/decompression method that compresses moving image data and decompresses the compressed moving image data into the original moving image data. The present invention relates to a moving image data compression/decompression device. Moreover, the present invention relates to a computer readable information recording medium on which a moving image data compression/decompression program is recorded.
Generally, image data has a large volume of information and requires a large memory capacity for storage and takes much time for data transmission. For that reason, various data compression techniques have been developed and used.
For data compression, realizing a compressibility as high as possible is important to reduce the memory capacity and transmission. Moreover, it is important to decrease degradation in image quality. However, it has been difficult to realize the high compressibility and high image quality at the same time. Various approaches have been made to solve such problems.
For example, JP-A No 331367/1996 discloses the technique of applying different data compression methods to the whole of an image and an important area of the image. For data compression, the whole of an image places importance on compressibility. An important area places importance on the image quality rather than compressibility.
Moreover, a moving image is created by displaying, in a switching mode, a frame, or a still image acting as a constituent unit, several tens times per second. Since each frame includes a large volume of information, data compression is particularly important to handle moving images. For example, the system in compliance with the MPEG (Motion Picture Experts Group) standard and the AVI (Audio Video Interleaved) by US Microsoft are used as the moving image compressing and expanding technique.
However, the existing moving image compression techniques such as MPEG system are not sufficient as to high compressibility and high quality. At present, there is a trade-off between both the characteristics.